Method of fractionating gasolinelike hydrocarbons



Jan. 15, 1935. c. R. WAGNER METHOD OF FRACTIONATING GASOLINE LIKEHYDROCARBONS Filed Feb. 25, 1952 @JP-Myne? I I W 777W Patented Jan.`l,15, 1935 1,988,061 PATENT OFFICE METHOD 0F FRAorroNArmG GAsorJN- LIKEHYDROQARBONS Cary R. Wagner,l Chicago,l`ll., assignor to The P ure 01lCompany, Chicago, Ill., a corporation of Ohio Application February z5,1932, serial Np. 595,120

This invention relates to improvementsin the art of fractionatingand'distilling low boiling paraflinic hydrocarbons;wherebyv to obtainvas va. final distillate a gasoline of improved quality for use as amotor fuel. A

Gasolines obtained by'the distillation of certain crude oils such, forexample, as those produced in the Michigan field, arecomposed ofparaiflnic hydrocarbons of a highly saturated order and contain highpercentages of normal heptane, normal octane and normal nonane. Due tothe presence of the saturated hydrocarbons specified in such gasoline,the latter pose sesses, at present, but relatively low value as a fuelfor modern internal combustion engines, since hydrocarbons of the typespecified, when employed as a' motor fuel, produce knocking ordetonation, and with certain types of the more highly developed internalcombustion engines having high compression ratios, the use of such fuelis practically impossible in the performance of desired engineoperation.

I have found that by careful fractionation, in a manner hereinafterspecified, normal heptane, normal octane and normal nonane may be re-Imoved from gasoline vapors, whereby when the latter are condensed andused as a motor fuel, the said fuel will possess greatly improvedproperties in theA matter of suppressing or minimizing detonation inthecylinders of an internal combustion engine when burned therein.

For a further understanding of the invention, reference is to be had ltothe following description and the. accompanying drawing, wherein thefigure indicates diagrammatically apparatus employed in the carrying outof the present invention in one of its preferred embodiments.

Referring more particularly to the drawing, the numeral 3 -designates atank adapted to contain crude oil, suchas that obtained from or havingthe characteristics of Michigan crude. This oil is charged to a seriesof heated fractionating towers, which towers are designated in theirorder of operation by the numerals 4, 5, 6 and 7. Preferably, thesetowers are of standard construction but should be capable of effectingsharp fractionation and since there are many fractionating towers nowavailable having this desired property, itis considered unnecessary todescribe and illustrate in detail the structural features of such atower.

The oil from the tank 3 enters the bottom of the tower 4 and is thereinheated to vaporize low boiling compounds. These vapors are subjected 'tothe action of descending reflux condensate so that the vapors dischargedfrom the upper end of the tower through the pipe line 8 will comprise alight cut having an end point of approximately 190 F. From the side ofthe tower 4, there is taken oif a stream containing fractions boilingbetween F. and' 305 F., while a topped crude will be removed from thebottom of the tower 4 by way of the line' 9..

, This topped crude is conducted by way of the line 9 to the heatedlower part of the tower '7, the final tower in the series, and theremaining gasoline fractions are removed fromy the crude at this point.vThe side stream taken from the tower 4 passes through a pipe line 10and is delivered to the heated lower portion of the second tower 5. Thisside stream contains normal heptane, normal octane and normal nonanetogether with two fractions of good gasoline hydrocarbons boiling in theranges between the boiling points oithe pure parafiin hydrocarbonslmentioned. From the top of the tower 5 there ual oils, which collect inthe bottom of the tower 5, represents a narrow boiling point fractionhaving arange of approximately 290 to 305 F., and this fraction containsthe normal nonane content of the crude. This last described fractioncontaining normal nonane, vis transferred from the bottom of the tower 5by way of a pipe line 11 to a storage tank 12.

A side cut is taken from the tower 5 and is delivered to the heatedlower portion of the third fractionating tower 6. From the top of thistower, a good gasoline fraction, having a boiling point range of from210 to 240 F. is taken offand from the bottom of the tower 6 anothergood gasoline fraction, having a range of 255- to 290 F. is taken oi,while the normalA octane fraction is taken out of the tower 6 as a sidestream through a pipe line 13 with a distillation range of 240 to 255 F.

lBy combining the fractions from the top of the tower 4, Athe top of thetower 'l and from octane number approximately the same as that ofordinary Mid-continent gasoline, which is approximately 50. Michiganstraight run gasoline normally has an -octane number varying between 15and 30. Since the octane number of normal heptane is zero and normaloctane and normal nonane are considerably below lzero* on the octanescale, and since approximately six to eight per cent. of the crude oilfrom the field mentioned consists of these three paran hydrocarbons, itwill be apparent that a desired improvement is effected by the operationof the present invention in the combustion characteristics of suchstraight run gasoline. The desired gasoline is collected 'in a tank 14and the vapors lead from the top of the tower 4, the top of the tower 7and the top of the -tower 6 may be condensed as at 15 prior to theirdelivery to the tank 14 and, likewise, the liquid oils withdrawn fromthe bottom of the tower 6 may be cooled before entering the tank 14.'

What is claimed is:

1. In the non-destructive distillation of crude oils composed largely ofsaturated parailinic hydrocarbons, the process which consists insubjecting such crude oil to distillation in a plurality of seriallyconnected heated fractionating and distilling zones, removing as vaporsfrom the rst of said zones vaporized hydrocarbons having a boiling rangebelow that of normal octane, normal heptane and normal nonane, removingfrom an intermediate portion of the first of said zones hydrocarbonsfalling within the boiling range of gasoline and containing normalnonane, normal heptane and normal octane, subjecting said latterhydrocarbons in a second fractionating zone of distillation, removingfrom the upper portion of the second fractionating zone hydrocarbonscontaining normal heptane, removing from the lower portion of saidsecond fractionating zone hydrocarbons containing normal nonane,transferring hydrocarbons containing normal octane from an intermediateportion of said second fractionating zone to a third fractionating zone,heating the hydrocarbons in the third fractionating zone to effect theremoval from an intermediate portion of this latter zone of hydrocarbonscontainingnormal octane, and collecting and condensing hydrocarbonsremoved from the upper portion of the rst fractionating zone and theupper and lower portionsof the third fractionating zone.

2. 'Ihe method of improving the anti-knock rating of straight rungasolines which comprises subjecting crude oil containing such gasolineto distillation in a fractionating zone, removing from the upper portionof said fractionating zone in a vaporous state hydrocarbons having aboiling range lower than that of normal nonane, normal heptane andnormal octane, removing from an intermediate portion of saidfractionating zone and delivering the same to a second fractionatingzonehydrocarbons containing normal heptane, normal nonane, normaloctane, subjecting the hydrocarbons in the second fractionating zone todistillation whereby to remove from the upper portion of this zonehydrocarbons having the boiling range of normal heptane, removing fromthe lower portion of the second zone hydrocarbons having the boilingrange of normal nonane, and removing from an intermediate portion of thesecond zone hydrocarbons containing normal octane, transferring thehydrocarbons containing normal octane to a third fractionating anddistilling zone, removing as vapors from the upper por` tion of -thethird zone hydrocarbons having a boiling range lower than normal octaneand substantially free from normal heptane and normal nonane, removingfrom an intermediate portion of the third zone hydrocarbons composed ofand falling within the boiling range of normal octane, transferringresidual oils from the bottom of the rst zone to a fourth distilling andfractionating zone, condensing andv collecting vapors removed from theupper portions of the first, third and fourth fractionating zones andoils removed from the lower portion of the third zone to"provideanimproved gasoline substantially free from normal nonane, normalheptane and normal'octane, and removing from the bottom of the fourthzone oils' having a boiling range higher than that of gasoline.

3. 'Ihe method of fractionating gasoline vapors of the type containingnormal heptane, normal octane, and normal nonane whichv consists inpassing such vapors through a rst fractionating zone, removing from theupper portion of said zone vapors of hydrocarbons boiling belowapproximately 190 F., removing from an intermediate portion of thefractionating zone hydrocarbons having a boiling range of -approximately190 to 305 F., passing said latter hydrocarbons through a secondfractionating zone, removing from the top of the second fractionatingzone vapors of hydrocarbons boiling between approximately 190 to 210 F.and containing normal heptane, removing from the lower part of thesecond fractionating zone hydrocarbons having a boiling range of from290 to 305 F. and containing normal nonane, removing from anintermediate part of the second fractionating zone hydrocarbons boilingbetween approximately 210 F. and 290 F., 'passing said latterhydrocarbons through a third fractionating zone, removing from the topof the third fractionating zone hydrocarbons having a boiling range ofapproximately 210 to 240 F., removing from an intermediate portion ofthe third fractionating zone hydrocarbons having a boiling-range ofapproximately 240 to 255 Fand containing normal octane, removing fromthe bottom of the third fractionating zone hydrocarbons having a boilingrange of approximately 255 to290 F., transferring oils condensed in thebottom of the first fractionating tower. to a fourth fractionating towerand removing vapors from the top of the fourth fractionating tower andcondensing and collecting the same in common with vapors and oilsremoved from Athe top of the first zone and from the top and bottom ofthe third fractionating zone.

4. The process for treating vpetroleum oils composed largely ofhydrocarbons of the paraflin series and falling within the boiling rangeof ordinary gasoline to deprive such oils of unde sirable fractionswhich impair the anti-detonating value of said oils as motor fuel, whichcomprises subjecting such oils to non-destructive distillation tovaporize hydrocarbons contained therein falling within the boiling rangeof ordinary gasoline, fractionating said vaporized hydrocarbons andremoving therefrom in vaporous form light hydrocarbons having a boilingrange lower` than that of normal heptane, recovering from suchfractionation a distillate composed of hydrocarbons having boilingranges falling between and including those of normal heptane and normalnonane, subjecting said distillate to redistillation andsharply'separating therefrom as a vapor hydrocarbons composed solely ofthose fallin;l within the boiling -range of normal heptane, andrecovering a distillate from said second distillation step composed ofhydrocarbons having a boiling range higher than that of normal heptaneand in excess of that of normal octane, subjecting said last-nameddistillate to redistillation in a third zone, removing gasolinehydrocarbons in a vaporous state from said third zone, n

and recovering a distillate removed from said third zone as normaloctane.

` CARY R. WAGNER.

